In ocean thermal energy conversion systems, such as that shown in U.S. Pat. No. 4,441,321, granted Apr. 10, 1984, the difference in temperature between the surface water, normally at about 20 or 25 degrees C. and cold water (approximately 5 degrees C.) from a few hundred meters below the surface of the ocean, is employed to generate power in a turbine or the like. This power generation may be accomplished in a large number of ways, and the patent identified above employs a mist lift geometry in the implementation of the power generation.
In bringing the cold water from the depths of the ocean, relatively large quantities of water are required, and the depth from which it must be brought may be as much as five hundred or six hundred meters. The diameter of a suitable pipe as included in previously proposed OTEC systems, may be in the order of 8 feet or even up to 30 feet, for large power generating capacity units. The cost of the cold water pipe for a relatively small OTEC plant may be in the order of several million dollars, and may represent nearly one-third of the cost of the unit.
Accordingly, a principal object of the present invention is to reduce the cost of bringing cold water from the depths of a body of water up to the vicinity of the surface of the water.